Geomechanics for Energy and the Environment最新文献

Development of experimental system for rock anisotropic seepage under true triaxial stress

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-23 DOI: 10.1016/j.gete.2025.100677

Yixin Liu , Yan Gao , Gang Wang , Weimin Cheng , Chuanhua Xu , Jiaxin Cheng

In order to study the mechanical properties and anisotropic seepage behavior of rocks under complex stress conditions in deep strata, an anisotropic seepage dynamic monitoring system for true triaxial stress conditions was developed. In the process of research and development, four key technologies have been successfully broken through: (1) the use of an independently designed sealing system ensures complete sealing during seepage experiments, reduces experimental errors, and eliminates the edge effect through the six-axis linkage technology; (2) the specially designed multifunctional platen is capable of hydraulic fracturing, seepage, and data acquisition in the true triaxial experiments; (3) Integrated acoustic emission and seepage monitoring system, which can realize real-time dynamic monitoring of crack extension and seepage evolution under real triaxial stress conditions; (4) The control system supports real triaxial stress loading of up to 280 MPa, and it has a stress response sensitivity of 0.5 kPa/s, which ensures high-precision loading and monitoring. The crack extension modes of rocks under true triaxial stress conditions were systematically studied to reveal the dynamic relationship between crack extension and seepage paths. The results show that cracks preferentially extend in the direction of maximum principal stress, leading to a significant increase in seepage rate, while seepage rate lags in the direction of minimum principal stress due to the crack closure effect. A nonlinear "rise-decline-rise" dynamic relationship was observed between crack extension and seepage rate. This study provides new insights into the coupling mechanism between crack extension and seepage behavior under complex stress conditions.

{"title":"Development of experimental system for rock anisotropic seepage under true triaxial stress","authors":"Yixin Liu , Yan Gao , Gang Wang , Weimin Cheng , Chuanhua Xu , Jiaxin Cheng","doi":"10.1016/j.gete.2025.100677","DOIUrl":"10.1016/j.gete.2025.100677","url":null,"abstract":"<div><div>In order to study the mechanical properties and anisotropic seepage behavior of rocks under complex stress conditions in deep strata, an anisotropic seepage dynamic monitoring system for true triaxial stress conditions was developed. In the process of research and development, four key technologies have been successfully broken through: (1) the use of an independently designed sealing system ensures complete sealing during seepage experiments, reduces experimental errors, and eliminates the edge effect through the six-axis linkage technology; (2) the specially designed multifunctional platen is capable of hydraulic fracturing, seepage, and data acquisition in the true triaxial experiments; (3) Integrated acoustic emission and seepage monitoring system, which can realize real-time dynamic monitoring of crack extension and seepage evolution under real triaxial stress conditions; (4) The control system supports real triaxial stress loading of up to 280 MPa, and it has a stress response sensitivity of 0.5 kPa/s, which ensures high-precision loading and monitoring. The crack extension modes of rocks under true triaxial stress conditions were systematically studied to reveal the dynamic relationship between crack extension and seepage paths. The results show that cracks preferentially extend in the direction of maximum principal stress, leading to a significant increase in seepage rate, while seepage rate lags in the direction of minimum principal stress due to the crack closure effect. A nonlinear \"rise-decline-rise\" dynamic relationship was observed between crack extension and seepage rate. This study provides new insights into the coupling mechanism between crack extension and seepage behavior under complex stress conditions.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100677"},"PeriodicalIF":3.3,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Study on the interaction between pile and soil under lateral load in coral sand 珊瑚砂中横向荷载作用下桩与土的相互作用研究

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-11 DOI: 10.1016/j.gete.2025.100674

Bingxiang Yuan , Qingyu Huang , Weiyuan Xu , Zejun Han , Qingzi Luo , Guorong Chen , Junhong Yuan , Qiyong Zhang , Sabri Mohanad Muayad Sabri

In complex marine environments, research on the response of single piles to lateral loads under different coral sand grain sizes and different embedment depths of the pile body is relatively limited. This study employed indoor scaled-model tests combined with PIV technology, focusing on two variables: coral sand particle sizes and embedment depths of rigid piles. The effects on the bending moment of single piles, the resistance of coral sand, and the displacement of the pile shaft and pile top in coral sand layers were analyzed. The study also revealed the distribution and development patterns of horizontal strain in coral sand particles around the pile top when subjected to lateral loads. The results showed that, as particle size decreased, the maximum bending moment of the pile and the resistance of coral sand increased, the rotation point of pile displacement rose, and pile top displacement increased. In addition, smaller particles had weaker interlocking, resulting in less effective force chain transmission and lower load diffusion. When the embedment depth of the rigid pile decreased, lateral loads could not be transferred to deeper soil layers, leading to more noticeable displacements at the pile shaft and pile top.

{"title":"Study on the interaction between pile and soil under lateral load in coral sand","authors":"Bingxiang Yuan , Qingyu Huang , Weiyuan Xu , Zejun Han , Qingzi Luo , Guorong Chen , Junhong Yuan , Qiyong Zhang , Sabri Mohanad Muayad Sabri","doi":"10.1016/j.gete.2025.100674","DOIUrl":"10.1016/j.gete.2025.100674","url":null,"abstract":"<div><div>In complex marine environments, research on the response of single piles to lateral loads under different coral sand grain sizes and different embedment depths of the pile body is relatively limited. This study employed indoor scaled-model tests combined with PIV technology, focusing on two variables: coral sand particle sizes and embedment depths of rigid piles. The effects on the bending moment of single piles, the resistance of coral sand, and the displacement of the pile shaft and pile top in coral sand layers were analyzed. The study also revealed the distribution and development patterns of horizontal strain in coral sand particles around the pile top when subjected to lateral loads. The results showed that, as particle size decreased, the maximum bending moment of the pile and the resistance of coral sand increased, the rotation point of pile displacement rose, and pile top displacement increased. In addition, smaller particles had weaker interlocking, resulting in less effective force chain transmission and lower load diffusion. When the embedment depth of the rigid pile decreased, lateral loads could not be transferred to deeper soil layers, leading to more noticeable displacements at the pile shaft and pile top.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100674"},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fracture properties and creep behavior of humic and sapropelic coals from nanoindentation measurements

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-11 DOI: 10.1016/j.gete.2025.100672

Jianfeng Wang , Huijuan Guo , Zhongyang Ma , Tian Liang , Chao Yang , Yuke Liu , Peng Liu , Dayong Liu , Ping'an Peng , Yongqiang Xiong

The fracture properties and creep behavior of coal and its macerals play a critical role in coal mining and exploration, hydraulic fracturing operations, improving the efficiency of (enhanced) coalbed methane recovery, the implementation of geological carbon sequestration technology, and deep underground coal gasification technology. Previous researchers have mainly focused on micromechanical parameters such as Young's modulus and hardness, while it is currently unclear how organic macerals affect their fracture properties (fracture toughness (K_c), brittleness index (B)) and creep behavior of coal. Here, X-ray diffraction, Raman spectroscopy, and nanoindentation were used to investigate the microstructure, fracture properties and creep behavior of sapropelic and humic coals. Results show that the variation of fracture parameters (K_c and B) is similar to the variation of hardness and Young's modulus for different coal macerals. Humic coal exhibited higher brittleness index and creep parameters (viscoelastic parameters (E₁, E₂, η₁, and η₂), and contact creep modulus (C)) compared to sapropelic coal. In addition, the fracture parameters (K_c and B) and the creep parameters (E₁, E₂, η₁, η_2, C_, and creep stress exponent (n)) of coal macerals decrease in the order: inertinite > vitrinite > alginite. This suggests that the sapropelic coal and alginite with lower brittle were more prone to creep. The changes in the microfracture and creep parameters of coal maceral are mainly determined by its chemical structure. This study improves the understanding of the fracture properties and creep behavior in the coal and its matrix at the micro scale, which will provide theoretical guidance for optimizing coal seam fracturing and shed light on the creep mechanism of coal.

{"title":"Fracture properties and creep behavior of humic and sapropelic coals from nanoindentation measurements","authors":"Jianfeng Wang , Huijuan Guo , Zhongyang Ma , Tian Liang , Chao Yang , Yuke Liu , Peng Liu , Dayong Liu , Ping'an Peng , Yongqiang Xiong","doi":"10.1016/j.gete.2025.100672","DOIUrl":"10.1016/j.gete.2025.100672","url":null,"abstract":"<div><div>The fracture properties and creep behavior of coal and its macerals play a critical role in coal mining and exploration, hydraulic fracturing operations, improving the efficiency of (enhanced) coalbed methane recovery, the implementation of geological carbon sequestration technology, and deep underground coal gasification technology. Previous researchers have mainly focused on micromechanical parameters such as Young's modulus and hardness, while it is currently unclear how organic macerals affect their fracture properties (fracture toughness (<em>K</em><sub>c</sub>), brittleness index (<em>B</em>)) and creep behavior of coal. Here, X-ray diffraction, Raman spectroscopy, and nanoindentation were used to investigate the microstructure, fracture properties and creep behavior of sapropelic and humic coals. Results show that the variation of fracture parameters (<em>K</em><sub>c</sub> and <em>B</em>) is similar to the variation of hardness and Young's modulus for different coal macerals. Humic coal exhibited higher brittleness index and creep parameters (viscoelastic parameters (<em>E</em><sub>1</sub>, <em>E</em><sub>2</sub>, <em>η</em><sub>1</sub>, and <em>η</em><sub>2</sub>), and contact creep modulus (<em>C</em>)) compared to sapropelic coal. In addition, the fracture parameters (<em>K</em><sub>c</sub> and <em>B</em>) and the creep parameters (<em>E</em><sub>1</sub>, <em>E</em><sub>2</sub>, <em>η</em><sub>1</sub>, <em>η</em><sub>2,</sub> <em>C</em><sub>,</sub> and creep stress exponent (<em>n</em>)) of coal macerals decrease in the order: inertinite > vitrinite > alginite. This suggests that the sapropelic coal and alginite with lower brittle were more prone to creep. The changes in the microfracture and creep parameters of coal maceral are mainly determined by its chemical structure. This study improves the understanding of the fracture properties and creep behavior in the coal and its matrix at the micro scale, which will provide theoretical guidance for optimizing coal seam fracturing and shed light on the creep mechanism of coal.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100672"},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantitative assessment of well leakage, part II: Case studies for CCS

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-11 DOI: 10.1016/j.gete.2025.100675

Al Moghadam , Sahar Amiri

This paper presents the second part of a two-part series on estimating fluid migration along wells. We use the results of the model described in the first paper and outline a leakage calculation methodology. The present method considers the mechanical behaviour of the flow pathway, formation creep, visco-inertial effects, and the operational conditions of the well to provide a deterministic evaluation of fluid migration along the well. Two case studies are presented that focus on a CO₂ injection well in a depleted reservoir and a legacy well in an aquifer CCS project.

The results indicate that there is a pressure threshold below which CO₂ may not flow through the cemented annulus. Beyond that point, the flow rate increases non-linearly with storage pressure. The size of the leakage pathway changes over time with the pressure and temperature of the system and is not a static parameter. Visco-inertial effects and creep could reduce the potential leak rate. The computed rates should be considered as an upper bound in this work as the impact of multiphase flow was not considered. This type of assessment is critical to conduct quantitative risk assessments for CCS projects. The results enable operators to manage storage pressure, reduce the cost of MMV (Measurement, Monitoring, and Verification) plans, and improve well designs. We argue that the impact of the magnitude of leakage rates reported in this work should be weighed against the improvements to the economics of CCS projects with an increased pressure/storage capacity.

{"title":"Quantitative assessment of well leakage, part II: Case studies for CCS","authors":"Al Moghadam , Sahar Amiri","doi":"10.1016/j.gete.2025.100675","DOIUrl":"10.1016/j.gete.2025.100675","url":null,"abstract":"<div><div>This paper presents the second part of a two-part series on estimating fluid migration along wells. We use the results of the model described in the first paper and outline a leakage calculation methodology. The present method considers the mechanical behaviour of the flow pathway, formation creep, visco-inertial effects, and the operational conditions of the well to provide a deterministic evaluation of fluid migration along the well. Two case studies are presented that focus on a CO<sub>2</sub> injection well in a depleted reservoir and a legacy well in an aquifer CCS project.</div><div>The results indicate that there is a pressure threshold below which CO<sub>2</sub> may not flow through the cemented annulus. Beyond that point, the flow rate increases non-linearly with storage pressure. The size of the leakage pathway changes over time with the pressure and temperature of the system and is not a static parameter. Visco-inertial effects and creep could reduce the potential leak rate. The computed rates should be considered as an upper bound in this work as the impact of multiphase flow was not considered. This type of assessment is critical to conduct quantitative risk assessments for CCS projects. The results enable operators to manage storage pressure, reduce the cost of MMV (Measurement, Monitoring, and Verification) plans, and improve well designs. We argue that the impact of the magnitude of leakage rates reported in this work should be weighed against the improvements to the economics of CCS projects with an increased pressure/storage capacity.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100675"},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Study on the characteristics of coal pore structure changes during hot flue gas displacement and their impact on the gas displacement effect

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-05 DOI: 10.1016/j.gete.2025.100673

Jiahao He , Baiquan Lin , Tong Liu , Zhenyong Zhang , Shuai Le , Yajie Hu

Gas displacement by hot flue gas injection into the coal body is a hot spot in the research on high-gas and low-permeability coal seams. Injecting hot flue gas generated by gas power plants into coal seams will introduce water and CO₂, and the introduced CO₂ will dissolve and ionize to form an acidic environment, leading to the dissolution of minerals in coal. Therefore, it is particularly important to study the impact of coal pore structure changes on gas displacement before and after mineral dissolution. In this study, the impact of mineral dissolution in coal was explored by combining Computed Tomography (CT) and COMSOL Multiphysics numerical simulation, and the parameters of the numerical model were determined based on gas adsorption-desorption experimental results. The following conclusions were drawn at the millimeter scale: (1) Compared with the Langmuir equation, the BET equation is more competent to act as an isothermal adsorption and desorption model of coal in high-gas and low-permeability coal seams. (2) After 10.11 % of minerals dissolve, the flow velocity and outlet flow rate in the fractures formed at the original positions of minerals both increase significantly, and the model permeability grows from 7.0711 × 10⁻¹² m² to 2.2331 × 10⁻¹¹ m². (3) The time consumed for the residual gas pressure to drop from its initial value to 0.1 MPa was calculated. (4) After mineral dissolution, the coal pore structure alters, resulting in changes in the distribution of gas pressure during displacement, and the gas pressure varies obviously spatially.

{"title":"Study on the characteristics of coal pore structure changes during hot flue gas displacement and their impact on the gas displacement effect","authors":"Jiahao He , Baiquan Lin , Tong Liu , Zhenyong Zhang , Shuai Le , Yajie Hu","doi":"10.1016/j.gete.2025.100673","DOIUrl":"10.1016/j.gete.2025.100673","url":null,"abstract":"<div><div>Gas displacement by hot flue gas injection into the coal body is a hot spot in the research on high-gas and low-permeability coal seams. Injecting hot flue gas generated by gas power plants into coal seams will introduce water and CO<sub>2</sub>, and the introduced CO<sub>2</sub> will dissolve and ionize to form an acidic environment, leading to the dissolution of minerals in coal. Therefore, it is particularly important to study the impact of coal pore structure changes on gas displacement before and after mineral dissolution. In this study, the impact of mineral dissolution in coal was explored by combining Computed Tomography (CT) and COMSOL Multiphysics numerical simulation, and the parameters of the numerical model were determined based on gas adsorption-desorption experimental results. The following conclusions were drawn at the millimeter scale: (1) Compared with the Langmuir equation, the BET equation is more competent to act as an isothermal adsorption and desorption model of coal in high-gas and low-permeability coal seams. (2) After 10.11 % of minerals dissolve, the flow velocity and outlet flow rate in the fractures formed at the original positions of minerals both increase significantly, and the model permeability grows from 7.0711 × 10<sup>−12</sup> m<sup>2</sup> to 2.2331 × 10<sup>−11</sup> m<sup>2</sup>. (3) The time consumed for the residual gas pressure to drop from its initial value to 0.1 MPa was calculated. (4) After mineral dissolution, the coal pore structure alters, resulting in changes in the distribution of gas pressure during displacement, and the gas pressure varies obviously spatially.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100673"},"PeriodicalIF":3.3,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development and validation of TOUGH-3DEC: A three-dimensional discontinuum-based numerical simulator for coupled thermo-hydro-mechanical analysis

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-05 DOI: 10.1016/j.gete.2025.100670

Saeha Kwon, Kwang-Il Kim, Changsoo Lee, Jaewon Lee, Jin-Seop Kim

The discontinuum-based numerical methods can simulate the coupled thermo-hydro-mechanical (THM) processes in porous media with multiple discontinuities, so it is appropriate to model the mechanical behavior of a fractured host rock under the coupled processes such as a geological repository for high-level radioactive waste. TOUGH-3DEC, a three-dimensional discontinuum-based simulator for the coupled THM analysis, was developed by linking the integral finite difference method TOUGH2 and the distinct element method 3DEC to describe the coupled THM processes in porous media and discontinuous media. TOUGH2 handles the coupled TH analysis through the internal simulation module, while 3DEC performs mechanical analysis based on the constitutive models of porous media and discontinuity, coupling the thermal and hydraulic responses from TOUGH2. The thermal and hydraulic couplings are key processes and should be carefully verified by sufficient cases, so this study performed TM and HM verifications by modelling analytic solutions including the uniaxial consolidation, fracture static opening, and the heating of a hollow cylinder. As comparative validations, two models describing laboratory-scale experiments regarding the HM and TM processes of fractured rock were simulated and compared to the experimental results. The developed TOUGH-3DEC simulator showed sufficient accuracy in reflecting the coupled THM processes of the small-scale discontinuous rock, but still needs to be verified by more complicated and large-scale coupled process problems to be applicable to the demonstration of the field-scale model requiring the coupled THM processes of various geological media, such as a multi-barrier system of a geological repository.

{"title":"Development and validation of TOUGH-3DEC: A three-dimensional discontinuum-based numerical simulator for coupled thermo-hydro-mechanical analysis","authors":"Saeha Kwon, Kwang-Il Kim, Changsoo Lee, Jaewon Lee, Jin-Seop Kim","doi":"10.1016/j.gete.2025.100670","DOIUrl":"10.1016/j.gete.2025.100670","url":null,"abstract":"<div><div>The discontinuum-based numerical methods can simulate the coupled thermo-hydro-mechanical (THM) processes in porous media with multiple discontinuities, so it is appropriate to model the mechanical behavior of a fractured host rock under the coupled processes such as a geological repository for high-level radioactive waste. TOUGH-3DEC, a three-dimensional discontinuum-based simulator for the coupled THM analysis, was developed by linking the integral finite difference method TOUGH2 and the distinct element method 3DEC to describe the coupled THM processes in porous media and discontinuous media. TOUGH2 handles the coupled TH analysis through the internal simulation module, while 3DEC performs mechanical analysis based on the constitutive models of porous media and discontinuity, coupling the thermal and hydraulic responses from TOUGH2. The thermal and hydraulic couplings are key processes and should be carefully verified by sufficient cases, so this study performed TM and HM verifications by modelling analytic solutions including the uniaxial consolidation, fracture static opening, and the heating of a hollow cylinder. As comparative validations, two models describing laboratory-scale experiments regarding the HM and TM processes of fractured rock were simulated and compared to the experimental results. The developed TOUGH-3DEC simulator showed sufficient accuracy in reflecting the coupled THM processes of the small-scale discontinuous rock, but still needs to be verified by more complicated and large-scale coupled process problems to be applicable to the demonstration of the field-scale model requiring the coupled THM processes of various geological media, such as a multi-barrier system of a geological repository.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100670"},"PeriodicalIF":3.3,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143815438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental study on the swelling pressure of compacted bentonite under high temperatures above 100 °C

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-04-04 DOI: 10.1016/j.gete.2025.100671

Jang-Un Kim , Hyunwook Choo , Boyoung Yoon , Susan E. Burns

Disposal and storage of high-level nuclear waste in deep geological repositories requires understanding the behavior of compacted clay at high maximum design temperatures (> 100 °C); however, the effect of temperature variations on the swelling pressure of compacted bentonite has generally been examined within a restricted temperature range of 20–90 °C. Consequently, this experimental investigation uses specially designed temperature-controlled apparatus to determine the swelling pressure of compacted Na-bentonite across a temperature span of 10–160 °C. The poro-thermal and chemo-thermal effects on the swelling pressure of bentonite were studied using three dry densities (1.20, 1.35 and 1.50 Mg/m³) and three electrolyte concentrations (de-ionized water, NaCl 0.1 M and 0.5 M solutions). A linear relationship was observed between the normalized swelling pressure (the ratio of swelling pressure at a specific temperature to the swelling pressure at 25 °C) and temperature under the tested temperature ranges, suggesting that the swelling pressure measured at relatively low temperature ranges (below 100 °C) could be used to estimate the high temperature (above 100 °C) swelling pressure based on extrapolation. The swelling pressure increased with temperature, and higher dry densities and lower electrolyte concentrations amplified this effect. The complex interplay of dry density, pore fluid concentration, and temperature on the swelling behavior of compacted bentonite was explained based on the competition between the interlayer and interparticle swelling pressures.

{"title":"Experimental study on the swelling pressure of compacted bentonite under high temperatures above 100 °C","authors":"Jang-Un Kim , Hyunwook Choo , Boyoung Yoon , Susan E. Burns","doi":"10.1016/j.gete.2025.100671","DOIUrl":"10.1016/j.gete.2025.100671","url":null,"abstract":"<div><div>Disposal and storage of high-level nuclear waste in deep geological repositories requires understanding the behavior of compacted clay at high maximum design temperatures (> 100 °C); however, the effect of temperature variations on the swelling pressure of compacted bentonite has generally been examined within a restricted temperature range of 20–90 °C. Consequently, this experimental investigation uses specially designed temperature-controlled apparatus to determine the swelling pressure of compacted Na-bentonite across a temperature span of 10–160 °C. The poro-thermal and chemo-thermal effects on the swelling pressure of bentonite were studied using three dry densities (1.20, 1.35 and 1.50 Mg/m³) and three electrolyte concentrations (de-ionized water, NaCl 0.1 M and 0.5 M solutions). A linear relationship was observed between the normalized swelling pressure (the ratio of swelling pressure at a specific temperature to the swelling pressure at 25 °C) and temperature under the tested temperature ranges, suggesting that the swelling pressure measured at relatively low temperature ranges (below 100 °C) could be used to estimate the high temperature (above 100 °C) swelling pressure based on extrapolation. The swelling pressure increased with temperature, and higher dry densities and lower electrolyte concentrations amplified this effect. The complex interplay of dry density, pore fluid concentration, and temperature on the swelling behavior of compacted bentonite was explained based on the competition between the interlayer and interparticle swelling pressures.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"42 ","pages":"Article 100671"},"PeriodicalIF":3.3,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143807367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical simulation of coupled THM behaviour of full-scale EBS in backfilled experimental gallery in the Horonobe URL 对 Horonobe URL 回填实验走廊中全尺寸 EBS 的耦合 THM 行为进行数值模拟

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-03-29 DOI: 10.1016/j.gete.2025.100668

Yutaka Sugita , Hirokazu Ohno , Steffen Beese , Pengzhi Pan , Minseop Kim , Changsoo Lee , Carlos Jove-Colon , Carlos M. Lopez , Suu-yan Liang

Bentonite-based engineered barrier system (EBS) is a key component of many repository designs for the geological disposal of high-level radioactive waste. Given the complexity and interaction of the phenomena affecting the barrier system, coupled thermo-hydro-mechanical (THM) numerical analyses are a potentially useful tool for a better understanding of their behaviour. In this context, a Task (the Horonobe EBS experiment) was undertaken to study, using numerical analyses, the thermo-hydro-mechanical (and thermo-hydro) interactions in bentonite based engineered barriers within the international cooperative project DECOVALEX 2023. One full-scale in-situ experiment and four laboratory experiments, largely complementary, were selected for modelling. The Horonobe EBS experiment is a temperature-controlled non-isothermal experiment combined with artificial groundwater injection. The Horonobe EBS experiment consists of the heating and cooling phases. Six research teams performed the THM or TH (depended on research team approach) numerical analyses using a variety of computer codes, formulations and constitutive laws. For each experiment, the basic features of the analyses are described and the comparison between calculations and laboratory experiments and field observations are presented and discussed.

基于膨润土的工程屏障系统（EBS）是许多高放射性废物地质处置库设计的关键组成部分。鉴于影响屏障系统的各种现象的复杂性和相互作用，热-水-机械（THM）耦合数值分析是更好地了解其行为的潜在有用工具。在此背景下，在 DECOVALEX 2023 国际合作项目范围内开展了一项任务（Horonobe EBS 实验），利用数值分析研究基于膨润土的工程屏障中的热-水-机械（和热-水）相互作用。我们选择了一个全面的现场实验和四个实验室实验进行建模，这些实验在很大程度上是互补的。Horonobe EBS 实验是一项温控非等温实验，结合了人工地下水注入。Horonobe EBS 实验包括加热和冷却两个阶段。六个研究小组利用各种计算机代码、公式和构成法则进行了 THM 或 TH（取决于研究小组的方法）数值分析。对于每个实验，都描述了分析的基本特征，并介绍和讨论了计算与实验室实验和现场观测之间的比较。

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引用次数: 0

Numerical investigation of the gas-induced fracturing behavior of the Callovo-Oxfordian claystone

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-03-28 DOI: 10.1016/j.gete.2025.100669

Carlos Plúa , Rémi de La Vaissière , Gilles Armand , Sebastià Olivella , Alfonso Rodriguez-Dono , Zhan Yu , Jian-fu Shao , Eike Radeisen , Hua Shao

This paper presents a synthesis of the numerical approaches adopted by three research teams to reproduce gas fracturing initiation in the Callovo-Oxfordian claystone. This collaborative work has been carried out within the framework of the DECOVALEX-2023 project. First, the research teams investigated the impact of gas migration and fluid pressurization within the Callovo-Oxfordian claystone and the fracturing threshold pressure through a series of benchmark exercises under plane strain conditions with increasing complexity. The three numerical approaches accounted for couplings between the mechanical part and hydraulic parameters, such as permeability, through different variables such as damage, fracture aperture, or equivalent plastic strain. Then, the research teams utilized their models to reproduce two injection tests at the field-scale. A challenge faced by the research teams was dealing with a single study point per injection test, complicating the study of responses near the injection interval. This part included interpretative analyses with simplified approaches for a better understanding of gas pressure build-up. Overall, the numerical simulations yielded acceptable results in reproducing the in-tests after a calibration process and provided insights into the hydromechanical response of the Callovo-Oxfordian claystone under two-phase flow conditions. Nonetheless, the benchmark exercises showed that the numerical results using different mechanical constitutive models yielded different outcomes when reaching critical values leading to fracturing, which strongly depend on how the mechanical part influences the hydraulic response through the changes in hydraulic properties.

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引用次数: 0

Effects of chemical pollution from different pH solutions on evaporation and crack growth of granite residual soil

IF 3.3 2区工程技术 Q3 ENERGY & FUELS

Geomechanics for Energy and the Environment

Pub Date : 2025-03-27 DOI: 10.1016/j.gete.2025.100667

Yang Chen , Liansheng Tang , Weiya Ding , Zihua Cheng

In recent years, soil chemical pollution has emerged as a significant global environmental concern. Soil cracking induced by chemical pollution can alter the movement of water in the soil, consequently influencing the entire geological environment. Nevertheless, the consequences of diverse acid-alkali chemical pollutants on soil evaporation and cracking remain incompletely understood. In this investigation, the impact of varied pH chemical solutions on the evaporation and crack formation in granite residual soil (GRS) was examined. Mud samples were submerged in solutions of differing pH levels for 28 days while maintaining a constant temperature of 50°C. The findings demonstrate that as the pH of the solution increases, chemical pollution alters the inter-particle forces within soil, leading to an accelerated evaporation rate of GRS. At pH values of 3, 5, 7, 9, 11, and 13, the constant rate stage of soil water evaporation represented 78.9 %, 78.0 %, 76.1 %, 73.9 %, 69.6 %, and 69.0 % of the total evaporation time, respectively. Acid-alkali pollution significantly accelerates the development of cracks in GRS. For instance, at pH values of 3, 5, 9, 11, and 13, the final crack rate in soil samples increased by 56.56 %, 38.44 %, 19.06 %, 112.81 %, and 305.31 %, respectively, when compared to pH 7. The final fractal dimension of cracks increased by 2.29 %, 0.84 %, 0.63 %, 7.22 %, and 9.52 %, correspondingly. Varied pH levels in chemical solutions influence evaporation characteristics and crack development by altering the contact angle, the electric double layer (EDL), mineral composition, and the soil's microstructure. The research has uncovered an inverse relationship between the thickness of the EDL and contact angle or time of initial crack formation. Building upon this finding, a novel method is introduced to assess changes in EDL thickness. The findings of this study have practical implications for a range of applications related to hydrology and soil stability in the presence of acid-alkali pollution.

近年来，土壤化学污染已成为全球关注的重要环境问题。化学污染引起的土壤龟裂会改变土壤中水的流动，进而影响整个地质环境。然而，人们对各种酸碱化学污染物对土壤蒸发和开裂的影响仍不甚了解。本研究考察了不同 pH 值的化学溶液对花岗岩残积土（GRS）蒸发和裂缝形成的影响。在保持 50°C 恒温的情况下，将泥土样本浸没在不同 pH 值的溶液中长达 28 天。研究结果表明，随着溶液 pH 值的升高，化学污染会改变土壤中颗粒间的作用力，从而导致花岗岩残余土壤蒸发速度加快。在 pH 值为 3、5、7、9、11 和 13 时，土壤水蒸发的恒定速率阶段分别占总蒸发时间的 78.9%、78.0%、76.1%、73.9%、69.6% 和 69.0%。酸碱污染大大加快了 GRS 裂纹的发展。例如，当 pH 值为 3、5、9、11 和 13 时，与 pH 值为 7 时相比，土壤样本的最终裂缝率分别增加了 56.56 %、38.44 %、19.06 %、112.81 % 和 305.31 %，裂缝的最终分形维数也相应增加了 2.29 %、0.84 %、0.63 %、7.22 % 和 9.52 %。化学溶液中不同的 pH 值通过改变接触角、电双层（EDL）、矿物成分和土壤的微观结构来影响蒸发特性和裂缝发展。研究发现，EDL 厚度与接触角或初始裂纹形成时间之间存在反比关系。在这一发现的基础上，引入了一种新方法来评估 EDL 厚度的变化。这项研究的结果对一系列与酸碱污染情况下的水文和土壤稳定性有关的应用具有实际意义。

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引用次数: 0